Hi, I have a combi boiler installed in my attic. The hot water downstairs gets steaming hot, as does my shower upstairs and the tap in the sink upstairs but the tap in the bath only seems to get luke warm. Any ideas why this would happen?
Thanks.

I'm guessing that this is a new problem. It is quite possible that you have a malfunctioning bath valve. Single handle valves, like Moen, can allow cross over of cold and hot, making your tub colder. Make sure your shut-off valve is completely open; but it might be time for a new cartridge or valve assembly.